The effects of ionizing and ultra-violet radiation on nucleic acids and proteins and their constituents are being studied. The mechanism of the interaction of cancer chemotherapy agents with radiation is of interest, since such knowledge can be potentially useful in radiation therapy. The present report includes electron spin-resonance studies of radicals produced by gamma-irradiation and ultra-violet photolysis of nucleic acids, proteins, their constituents and of chemotherapy agents of the intercalating type (e.g., actinomycin D, adriamycin). BIBLIOGRAPHIC REFERENCES: Kominami, S. and Riesz, P.: ESR Studies of gamma-irradiated wet DNA. Radiat. Res. 67: 173-177, 1976. Kominami, S., Wee, V. T., and Riesz, P.: ESR Study of the effect of visible light on gamma-irradiated DNA and its constituents at 77 degrees K. Radiat. Res. 69: 213-222, 1977.